var bj = parseFloat(prompt('请输入本金：',''));
var nf1 = 1;
var nf3 = 3;
var nf5 = 5;
var lv1 = 0.002;
var lv3 = 0.004;
var lv5 = 0.006;

var bx1 = bj + bj * nf1 * lv1;
var bx3 = bj + bj * nf3 * lv3;
var bx5 = bj + bj * nf5 * lv5;

console.log(bx1);
console.log(bx3);
console.log(bx5);
